This invention relates generally to a commutator housing for an electric motor and a method for mounting the commutator in the commutator housing. In particular, the invention applies to an electric motor designed to drive motor vehicle equipment, such as a window regulator, a sunroof or a seat operation motor, for example.
French Patent 2,814,868 discloses an electric motor including a commutator.
A commutator usually includes a ring having a series of conductive segments around its circumference. The commutator ring is designed to be securely mounted on a rotor shaft.
An electric motor generally includes a stator frame and a rotor rotatably mounted in the stator. The motor also includes windings that are integral with the rotor shaft. Each winding is electrically connected to two diametrically opposed segments of the commutator.
The commutator is generally mounted in a commutator housing integral with the stator. The commutator housing includes a support having a central opening designed to receive the commutator and to allow the rotor shaft to pass through the support. The support is made of an insulating material, for example plastic.
The commutator housing also includes at least one pair of brushes that are diametrically opposed relative to the commutator and designed to contact the segments of the commutator during the rotation that is linked to the rotor shaft. The brushes are electrically connected to a supply of electric current.
When the motor, and in particular the commutator, is mounted in the commutator housing, the brushes must be prevented from contacting the commutator segments. Then, when mounting is complete, the brushes must be brought into contact with the commutator segments. The mechanical contact between the brushes and the commutator segments must be correctly ensured to guarantee satisfactory electrical contact with the windings connected to the segments.
Thus, the brushes of the commutator housing must be held in a first mounting position during the positioning of the commutator, and then the brushes must be held in a second contact position to ensure the brushes supply electricity to the commutator segments.
A commutator housing is known, for example installed on motors marketed by the assignee and listed under reference 420143. The commutator housing includes a device for locking the brushes. The housing of the prior art is illustrated schematically in FIGS. 1a and 1b, which shows the brushes in a mounting position and in a contact position, respectively.
The housing includes a plastic support 1 in which two casings 8 receiving brushes 5 are arranged. Each brush 5 includes an electrical connection formed by a copper braid 6 (a single connection is shown). The housing shown does not include a commutator, but has a central opening 2 designed to receive the commutator ring and the rotor through-shaft.
In the mounting position shown in FIG. 1a, the brushes 5 are retracted to the rear of the casing 8 and located on the opposite side of the opening 2 that is designed to receive the commutator. A spring 9 holds each brush 5 in the retracted mounting position.
In the contact position shown in FIG. 1b, the brushes 5 are housed in the casing 8, and the spring 9 provides pressure on the back of the brush 5 to push the brush 5 towards the commutator.
Thus, the spring 9 has the double function of holding the brush 5 in the mounting position and then in the contact position. However, the spring 9 constitutes a separate part from the plastic support 1 of the housing. It must therefore be manufactured separately and then mounted on the housing. Moreover, the bearing point of the spring 9 must be placed manually on the top of or on the back of the brush 5 to place the brush 5 in the mounting position and then the contact position. Moreover, the electrical connection of the brush 5 is also ensured by an additional component formed by the copper braid 6.
The numerous parts required for the satisfactory operation of the commutator housing increase its cost and complicate its production. Moreover, the movement of the brushes 5 from the mounting position to the contact position requires the manual intervention of an operator.
There is therefore a need for a simplified commutator housing that allows the brushes to be moved from a mounting position to a contact position in a simple, efficient and automatic manner.